The goal of the proposed research is to discover the general mechanisms that are involved in maintaining temporal organization within a multioscillator circadian sysdtem using the cockroach, Leucophaea maderae, as a model. Previous work has suggested that the pacemaker that drives the circadian rhythm of locomotor activity in the cockroach is composed of two, bilaterally paired and mutually coupled oscillators located in the optic lobes of the protocerebrum. Our research plan encompasses 3 specific objectives. (l) we plan to determine more precisely the anatomical locus of the pacemaking system, and to identify specific cells or tracts within the brain that either generate or carry phase information. These investigations will involve both a functional and structural analysis of regeneration of neural elements of the circadian system following optic tract section or optic lobe transplantation and an investigation of the temporal distribution of electrical and metabolic activity of specific cells or tracts within the brain using chronic recording and 2-deoxyglucose labeling. (2) The dynamics of internal coupling between oscillators will be studied using localized low-temperature pulses to transiently desynchronize pacemakers. (3) The output pathway of the pacemaker will be investigated, exploting our observations that following ablation of the optic lobes or damped oscillatory component of the circadian system can be driven by a temperature cycle. The completion of these studies will provide clues to general physiological principles that underlie circadian organization in multicellular organisms. This information should help us understand the consequences of disrupted circadian organization and the physiological penalties it entails.